Chlorine is what made 14 children ill at Calypso Water Park on Tuesday, the park confirmed.

Paramedics treated 14 kids and took 13 from Calypso to CHEO after they were swimming in the wave pool and suddenly began complaining of a strong chlorine smell and breathing problems, paramedics said.

Three of the children suffered nausea and vomiting and all 14 experienced upper airway irritation, which involves sore throat and coughing said paramedic spokesman J.P. Trottier.

In a statement released by Calypso Water Park through their public relations firm Massy Forget Langlois, the park said an air leak was detected by a maintenance technician and the filtration system was shut down for 15 minutes while both chlorine pumps ere kept running.

“As chlorine is highly volatile, it quickly evaporated due to the waves and emitted chlorine vapour, thereby irritating the lungs of 14 children, but no adults,” the statement read.

The wave pool includes several water return ports as part of a filtration process, as well as a slight undertow, which is why officials believe that only those in that pool were affected.

The statement said that although the “incident is regrettable” no one was seriously injured and maintenance technicians have been given a new procedure to follow to ensure all chlorine pumps are shut off when the filtration process is interrupted.

The Ottawa Citizen reports the water park was already under investigation by a provincial agency that monitors amusement park rides due to unrelated incidents involving injuries sustained by park visitors on water slides.